#循环实现n！
# n = int(input('input n:'))
# ret = 1
# for i in range(1,n+1):
#     ret *= i
# print(ret)

#递归实现n！
# def fun(n):
#     if n == 1:
#         return 1
#     return n * fun(n - 1)
# print(fun(5))

#函数的默认形参
# def add(x , y, b = False):
#     if b == True:
#         print(f'x = {x}, y = {y}')
#     return x + y
#
# print(add(3,5,True))

#关键字传参
# def sub(x,y):
#     print(x - y)
#
# sub(y=100,x=20)
